Hi all, I'm hoping the wealth of experience here will be able to solve my problem!

I've recently setup an OpenBSD 4.6 box to use as a dedicated firewall, got it configured, and all seems well - except that the packet filter is causing connection dropouts every few minutes or so.

e.g. If I try to download a large file, it will download for anywhere between 1 - 9 minutes, then simply hang, until I manually cancel. My connection to IRC is also dropped out constantly too.

I also bought 2 dedicated NICs (Dlink DGE-528T, supported Chipset) to use instead of the onboard gigabit NICs to see if they could be at fault, but the same thing occurs.
This is definitely a pf issue, as if I do a pfctl -d everything works fine from that point on.

If anyone has any idea as to what could be at fault in my configuration I'd be most grateful - after what little troubleshooting I can do at the moment, being somewhat of a BSD noob, all I can think of is forcing the adapters to 100/Mb & 1000/Mb.

Below are my ifconfig & pf.conf, and I also attached an image with systat output, with pf enabled on the left, and with it disabled on the right (my IRC connection got reset twice in the 6 minute period it was enabled). If any extra info. is needed I'd be happy to supply.